In the art of making roofing shingles and tiles for exterior application in the building industry, such products are made by compression molding of multi-component formulations, which comprise blends of virgin and recycled polymers and various low cost fillers.
In order to achieve low production costs, it is commonplace for manufacturers to use inexpensive raw materials, such as recycled resin of low quality with a very large amount of inexpensive filler derived from various waste streams. Such filler can include carbon black, recycled rubber tire crumb, coal fines, pulp and paper waste, and other inexpensive materials.
The use of large quantities of such fillers reduces the mechanical properties of the ultimate product, however. Additionally, the use of such large quantities of fillers limits the color variations that are possible in the products and makes the processing of the formulations into shingles and other exterior application building products very difficult.
Typically, roofing shingles and tiles made of such material having waste for filler do not provide good weather resistance for the products. Additionally, the warranty periods that can reasonable be provided for such products tend to be short in duration.
Furthermore, such building industry roofing products have relatively low impact strength, especially at low temperatures. Insofar as their available colors are concerned, such tend to be limited to the colors gray and black.
The present invention is aimed at providing for synthetic fabrication of roofing shingles or tiles for exterior application which are free of the above-mentioned deficiencies of the prior art.
The present invention involves a roofing shingle or tile for exterior application in the building industry, of synthetic material, comprising a core of inexpensive material completely encapsulated by a skin of a different material, preferably of a polymer having high weather resistance and the ability to be colored in various colors. The core material will generally be of greater thickness than that of the skin material.
The skin material is melted and molded in some manner, and cools and solidifies, and the less expensive but greater volume of molten core material is also molded, but is disposed inside the skin and both are allowed to cool and solidify, such that a core of less expensive material is encapsulated by a skin of greater quality, having high weather resistance, color acceptance, and other beneficial features, such as good impact resistance, longer lifetime warranty capability and, optionally, various surface design configurations.
The skin and core materials can be co-injected into the same mold cavity. Alternatively, the skin material and core material can be co-extruded from melted ingredients contained within different cavities of a mold, so that the skin material encapsulates the core material such that the skin material and core material are laminated together. Also, alternatively, the core material and skin material can each be compression molded and laminated together. Other alternative processes include co-extrusion followed by stamping or embossing, blow molding of the skin and core materials, or rotational or sequential molding.
Regardless of the method of making the composite skin-and-core roofing product, three dimensional relief can be built into the mold cavity configuration or applied in a post-molding stamping or embossing operation to be present in the skin, in order to simulate various natural materials such as wood shakes, tile, slate, etc.
Accordingly, it is an object of this invention to provide a multi-layer molded synthetic roofing shingle or tile, wherein a high quality thermoplastic skin layer of material completely encapsulates a lesser quality thermoplastic core layer of material, wherein each layer includes filler material to reduce material cost.
It is a further object of this invention to accomplish the above object, wherein the core material for the product is essentially a waste or recycled material.
It is a further object of this invention to accomplish the above objects, wherein the core material comprises the greater amount of material used in making the roofing shingle or tile.
Other objects and advantages of the present invention will be apparent from a reading from the following brief descriptions of the drawing figures, the detailed descriptions of the preferred embodiments, and the appended claims.